When use remesh mesh does not follow bones
Instead of Remesh, Decimate doesn't save vertex weights. So you can try to recreate weights using data transfer modifier.

So here is base setup. I have simple mesh, deformed by armature. But when I add Remesh, armature doesn't work:



Here how to solve this problem:


Copy mesh to other layer and remove Remesh and Armature modifiers on them. It will be a "Source". By the way, you can do a link instead a copy, by using Alt + D
Add a Data Transfer Modifier after Remesh but before Armature. In modifier settings set "Source" object, click Vertex data and vertex Group(s)